Utilisation of data in electronic form has become a part of everyday life. Most people are well acquainted with documents, music, videos etc., being available as application data in electronic form such as Word documents, MP3 music files, MPEG movie files, etc. Many users of electronic devices such as personal computers (PCs), portable music players, digital cameras etc. are also used to the concept of copying application data from one device to another, for example copying Word files from one PC to another. Application data can often be utilised on more than one device, or on more than one type of device. An example is given by any Word document, which can be processed on any personal computer, or by an MP3 file, which can be played on a personal computer as well as on a portable music player, or by a digital image file, which can be created on a digital camera and transferred to a personal computer for image processing.